Fix typo

Author: jdreesen

bundles/configuration.rst

@@ -370,7 +370,7 @@ In XML, the `XML namespace`_ is used to determine which elements belong to the
 configuration of a specific bundle. The namespace is returned from the
 :method:`Extension::getNamespace() <Symfony\\Component\\DependencyInjection\\Extension\\Extension::getNamespace>`
 method. By convention, the namespace is a URL (it doesn't have to be a valid
-URL nor does it need to exists). By default, the namespace for a bundle is
+URL nor does it need to exist). By default, the namespace for a bundle is
 ``http://example.org/schema/dic/DI_ALIAS``, where ``DI_ALIAS`` is the DI alias of
 the extension. You might want to change this to a more professional URL::